Generally, current optical ribbon technology limits ribbon geometry to a straight line. When such fiber optic ribbons have to follow a curved path on an optical board, the accuracy of the routing is compromised. In some cases, the fiber optic ribbons may rub against abrasive surfaces such as FR4 laminate or heat sinks. In particular, as telecom system components, such as ASICs and optical transceivers, generate ever-increasing amounts of heat, fans are used to cool the components by generating powerful air flows. These air flows may cause the optical ribbons vibrate against the abrasive surfaces, resulting in possible damage to the optical ribbon.
Forcing prior art optical ribbons into curved paths, or installing the ribbon in a way that forces the optical ribbon to bend in any plane other than perpendicular to its surface, subjects the optical ribbon to permanent torsional stresses that reduce the optical ribbon's life expectancy. Over time, the optical ribbon, in particular, ribbons without jackets, may split. Because all parallel optic transceivers currently on the market feature an interface orientation parallel to the printed wiring board on which the transceivers are mounted, most optical ribbons are in permanent torsional stress.
In addition, when numerous optical ribbons are to be assembled on a board, a constraining assembly sequence must be determined and followed during assembly. Furthermore, height limitations (if no curved ribbon cross-over is allowed) may create significant design constraints when the straight optical ribbons are used.
U.S. Pat. No. 4,496,215 to Shaheen et al. provides a flat optical ribbon which can include a curved pattern (as shown in FIG. 3 of the '215 patent). The optical fibers are embedded in a resin layer in a predetermined pattern. Thereafter, first and second surfaces layers are laminated to the resin. The first and second surface layers provide structural support to the optical fibers to protect the optical fibers from tensile and shear stresses. While this provides the ability to have a flat optical ribbon which can include a curved pattern, the substrates increase the cost of manufacturing the ribbon.
The present invention provides an optical flex circuit and/or cable assembly which overcomes the problems presented in the prior art and which provides additional advantages over the prior art, such advantages will become clear upon a reading of the attached specification in combination with a study of the drawings.